rename eos_assert to eosio_assert, implement is_account() api, and move implementation from apply_context.hpp to .cpp

added tests for the WASM currency contract and fixed issues it exposed, refactored contract initialization as a require_recipient where the logic of init vs apply is now in the wasm_interface

Added test for basic wasm contract loading/unloading.  Fixed bugs in the intrinsic code and made it impossible to complile with the same class of bugs in the future.  Did some basic style/renaming in the contracts directory and in the enclosed tutorial/doxygen files

Also since the API changes creeped into so much code,
decided to just go ahead and change the remaining code. #624